Sealing materials have heretofore been used and filled into joints and clearances for the purpose of keeping watertightness, airtightness or the like. For example, in the field of automobiles•vehicles, sealing materials are applied to individual sites upon assembly of parts, assembly of bodies, coating, assembly of equipments or fittings, etc., so as to prevent air, water, dust and/or the like from penetrating into body interiors. The sealing materials include shapeless sealing materials such as paste and shaped sealing materials such as rubber gasket.
Among these, the pasty sealing material can be applied to an application site by means of a sealing gun by hand or robot, and so it is excellent in productivity and commonly used in the field of automobiles•vehicles, and the like. However, when the application site is a deep and narrow groove part such as a V-shaped groove, the application has been difficult because the sealing gun has not been able to be put therein. When a sealing material having a high viscosity is used, the sealing material cannot be filled up to the bottom of the V-shaped groove part, which cause a problem on watertightness and airtightness. Even when the application site is a shallow V-shaped groove part, it is difficult for a sealing material to fill the groove part up to the bottom thereof when the sealing material has a high viscosity. When a sealing material having a low viscosity on the other hand, sag is caused, and the sealing material run out to other portions than the application site. Further, when the pasty sealing material was applied to an application site of which good appearance is required, the form of the sealed part has had to be arranged by hand after the application.
As the shapeless sealing materials, there have been known many materials each having a composition comprising a resin or polymer as a main component, and containing a plasticizer, a softening agent, a filler, a reinforcing agent, a curing agent, etc., including the pasty sealing materials. However, most of them are in the form of a paste solution or emulsion. In a sealing material of the reaction-curing type, a liquid polymer is used as a main component. Many of these sealing materials include the above-described problems attendant on the pasty sealing materials. A two-component sealing material of the reaction-curing type, in which a curing agent is mixed upon its use, involves problems that a mixing operation is complicated, and a curing speed is fast, and the curing speed varies according to environmental temperatures.
Rubber gaskets and the like among the shaped sealing materials are suitable for use in arranging at a joint surface between structure members, but unstable for use in filling in a narrow groove part to seal it. The shaped sealing materials include sealing materials formed into sheets, strings or the like. Since many of them are used by attaching each of them to an application site and applying a load thereto or pressing it, however, it is difficult to completely fill it into a groove part in a narrow and deep form such as a V-shaped groove. An adhesive tape for sealing equipped with a support is further difficult to be applied to an application site having a complicated form, a deep groove part or the like because of the thickness or hardness of the support.
The conventional string-like sealing materials have disadvantage that they are partially elongated during handling to be thinned, broken or loosened. Such a string-like sealing material is not only poor in handling property, but also difficult to form a sealed part with good appearance, and also has an possibility that a problem may arise as to watertightness and airtightness. Japanese Patent Publication No. 39654/1977 has proposed a sealing material obtained by winding a sealing material layer composed mainly of tacky synthetic butyl rubber around an elastic resilient stretch-resistant body in the form of string into a string-like member for the purpose of improving the defects of such string-like sealing materials. In this string-like sealing material, the sealing material layer composed mainly of tacky synthetic butyl rubber is formed around a spongy or hollow stretch-resistant body. The sealing material is applied to an application site by applying a load thereto or pressing it to achieve sealing making good use of the restoring force of the stretch-resistant body and the tack of the sealing material layer. This publication describes that the use of the sealing material permits forming a firm sealing relation that it is well compatible with irregular rough surfaces such as concrete and cut surfaces of wood and penetrates into the tissue thereof by the restoring force to be airtightly tack-bonded thereto by a mere pressing operation without need of a fusion-bonding operation under heat. Even when this sealing material is used by pressing it, however, a narrow and deep groove part such as a V-shaped groove, or the like cannot be completely filled with the sealing material.
The present inventors proposed a reactive adhesive composition cured by heating in Japanese Patent registration No. 2739152. This reactive adhesive composition is a composition comprising a saturated polyester resin which is solid at normal temperature, a (meth)acrylurethane oligomer having a viscosity of at least 100 cps at normal temperature and a heat-curing catalyst, and is useful as a thick-applied coating, sealing material, pate or the like. This reactive adhesive composition does not have flowability and has moderate tackiness and cohesive force at normal temperature and thus can be used in any form such as string, pellet, sheet or block.
However, the reactive adhesive composition specifically disclosed in this patent publication is cured under curing conditions as its form is substantially retained. For example, it is disclosed that the reactive adhesive composition formed into a sheet is cured in that state without melting and flowing under curing conditions though its corners are rounded by melting. The use of such a reactive adhesive composition makes it difficult to completely fill a narrow and deep groove part such as a V-shaped groove with the adhesive composition